(Oregon Coast) – Not one but two kinds of somewhat unusual strandings are being reported up and down the Oregon coast in recent days, thanks to that run of stormy weather out of the west earlier in the week. Hordes of purple jellyfish have been cast up onto the sands – a periodic occurrence that isn't too rare in the region. But what does seem to be rarer is what is being washed up with them: tiny creatures that are their predators. (Photo above by Tiffany Boothe, Seaside Aquarium: what the beaches looked like this weekend).

The big visible stranding is of a small, rounded jellyfish called velella velella – or Purple Sails. They're also called By-the-Wind Sailors. Thousands of them are being found on just about every beach along the coastline.

Tiffany Boothe, of the Seaside Aquarium, was among the first to report them in the Seaside area. Her photos show the sheer numbers.

Down on the central coast, at Tillicum Campground near Yachats, a volunteer member of CoastWarch joined in the beach cleanup activities on Saturday and noticed a massive amount of them that day.

“The Beached by-the-Wind Sailors were not nearly as numerous as I remember them being last year,” the volunteer said on the organization's online reports.

“It's all due to that shift in southerly weather we had,” Plybon said.

Boothe said the velella velella have a clear “sail” that catches the wind and pushes them across the ocean surface. They are fairly common off these waters, but it takes a sizable west wind push to get them on land.

Once washed ashore, they can have another predator – although they die fairly quickly. They soon become food for a variety of beach-dwelling creatures. If they aren't eaten soon, they dry into the translucent “sails” you see on the beach. Then they start to have the unpleasant after effect of smelling pretty nasty. The beaches can have an ugly, fishy stink until they disappear.

They somewhat disappeared for several years until last year, showing not very often between 2007 and 2013. You'd find strandings fairly regularly between 1999 and 2005, and this would create an awful and stifling stink along the beaches when it happened. Several times in the spring and early summer you had to keep your window closed while driving 101.

Boothe described what velella velella eat.

“Purple Sails do not sting their prey; they capture their food with small sticky tentacles,” she said. “Velellas feed on fish eggs and small planktonic copepods. They can reach a size of 4 inches in length and 3 inches in width.”